I'm in a trade union and here in Sweden we support the Left party because they support trade unions - e.g. in the 80s there were proposals for having union members on the board, having unions own a stake in the companies, etc. - these all would have helped a lot with the current mass layoffs and inflation.
Speaking of the US, the unionised work there is terrible: at 4PM they would drop everything and come back the next day. No overtime, no nothing. You can't do a rush job or anything, they worked at their own pace and they didn't care about our deadlines and stuff. Its like dealing with government employees.
On the other hand, working with non-union people was great. They would put in the hours with no fuss, and obviously get paid for overtime and stuff. But you could actually get them to work as much as possible in a day.
When given a choice, people prefer not to be overworked due to poor management/scheduling/greed. When given a choice, people prefer to have stability in employment. This is demonstrated by the fact that when they have collective power these are two of the common items they negotiate for. Unions are created to promote their members interests. There, now you understand unions :) They represent the interest of their members not the companies interests and not letting workers pay the price for poor management/scheduling/overcommitments (I think this is where you are getting confused).
Unions don't care to 'force companies' anything, They care to represent THEIR members priorities. What you are promoting are a company's priorities which the company already looks out for and would be a strange thing for unions to form to then also promote.